The present invention, generally, relates to vehicle training simulators in which an image pick-up assembly traverses a terrain model in order to present an image of the terrain to an operator who is being trained on the simulator. More particularly, the image pick-up assembly is of the type which usually has a television camera and a terrain-following head unit to traverse the terrain model. The terrain-following head unit has an optical system to transmit an image of the terrain to the television camera.
In a known image pick-up assembly described in British Pat. No. 2,014,918 which is assigned to the same Assignee as the present invention, the optical system of the terrain-following head unit consists of a mirror arranged at about 45 degrees to reflect the view of the terrain as seen in a generally horizontal direction into the television camera which is mounted with its optical axis substantially perpendicular to the generally horizontal direction of view. The terrain-following head unit is clamped rigidly to the vertically-extending television camera.
An articulated shoe representing a scaled-down vehicle profile is arranged at the bottom of the terrain-following head unit to traverse the terrain model. As the television camera is moved across the terrain model, the articulated shoe is in contact with the surface of the terrain model and follows the terrain model contours in three axes, i.e., pitch, roll, and heave.
There are two "position" transducers in contact with the articulated shoe that sense the pitching and rolling movements. Heave movements resulting in a change in the height of the articulated shoe relative to the terrain-following head unit are measured by a separate "position" transducer.
The measured pitch movements of the articulated shoe are used to control rotation of the mirror in the optical system about a horizontal axis through one-half the angle of rotation of the articulated shoe in order to maintain the required line-of-sight. The measured roll movements of the articulated shoe are transmitted to a Dove prism in the optical system, which causes the image to be rotated to correspond with the roll of the articulated shoe. The mirror, which represents the operator's eye position, is maintained at a predetermined height above the surface of the terrain model by a height servo loop.
The present invention, however, differs from the above-identified British Patent in the provision which this invention has for protection of the terrain-following head unit from damage resulting from collision with features on the terrain model.
The terrain-following head unit must be sufficiently small to move over the terrain model in a realistic way and must necessarily pass close to features on the terrain model, such as buildings, trees, rocks, and the like. Because of the inexperience of the operators being trained, they may crash the terrain-following head unit into features on the terrain model.
In the prior equipment, the articulated shoe and the mirror of the optical system were each mounted separately in such a way as to be displaceable against springs in the event of contact with features on the terrain model, and such displacement resulted in the operation of a micro-switch to signal a dangerous condition and to stop the training exercise. This required a complex mounting structure which undesirably increased the overall dimensions of the terrain-following head unit and, thus, reduced both accuracy and realism. Also, it was responsive only to forces applied to the terrain-following head unit in particular directions.
Another image pick-up assembly with which the present invention is useful is that disclosed in U.S. Pat. No. 4,365,960 to Reed et al. and assigned to the same Assignee as the present invention.